Twist-off bottle caps were introduced in the 1960s in Germany. They are sealed on the bottle with screw threads instead of engaging a flange in the manner of a crown cap.
Polyethylene terephthalate, also known as PET was developed in 1941 and since the 1970s, soda bottles have been made by stretch blow molding, PET. For sealing blown PET bottles, which are widely used for packaging carbonated drinks, such caps are injection molded from plastic.
The number of threads in fizzy drink bottles are standardized. The dimension of the cap for a PET bottle is determined by the mouth of the bottle which is designed to be easily poured from, but, for packaging fizzy drinks, is relatively small to minimizing gas escaping.
Such lids vary somewhat, but for capping bottles of carbonated beverages, are typically about 15 mm high and approximately 30 mm in internal dimensions. They have a circular top surface and a torroidal skirt extending there around with a screw thread on the inner surface for engaging the corresponding male thread around the neck of the bottle. The number of threads per unit length and their pitch is standardized, but occasionally the threads are incomplete for aesthetic reasons as much as anything. Such lids are also provided with a polyethylene insert which is squashed against the mouth of the bottle providing a pressure resistant, water tight, and virtually CO2 tight seal.
Of necessity, such caps are tight fitting to the bottle neck thereunder to prevent the CO2 from escaping from carbonated beverages contained within the bottle.
Typically, the outer surface of the skirt is fluted to make it easier to grip. The edge joining the torroidal surface and the flat top is typically curved and sometimes the torroidal surface is slightly frustoconical, tapering slightly towards the substantially flat surface. The skirt typically terminates with a smooth ring. Such caps are produced by injection moulding.
It is well documented that the infirm, elderly, handicapped and children sometimes have difficulty opening such bottles. Furthermore, such bottles are typically 1½ or 2 liter capacity and are designed to be closable so that the contents need not be consumed at once. To retain some of the fizz, and to provide some shelf life without all the carbon dioxide escaping, it is necessary to tightly close such bottles once opened, and this is also difficult for the physically challenged to accomplish since the fluted skirt which is generally only one or two millimeters wider in diameter than the bottle neck itself, does not provide much grip nor much leverage.
There are a number of patents that relate to lids with easy grips for aiding opening by the infirm or children.
For example JP2009007065A2 provides a lid with a polygonal external surface for easy grip. Such lids provide short flat surfaces separated by large obtuse angles for gripping, and this provides only slightly more grip than the fluted skirt solution. Fingers typically slip off rather than find a purchase. Such lids are also inappropriate looking for bottles, since the angularity of the lid contrasts, rather than complements the smooth curves of the bottle. Indeed lids with polygonal shapes are reminiscent of nuts and bolts and are more appropriate for lubricants, oils and petroleum, distilled water for car batteries, antifreeze and other fluids for use in machinery rather than for capping bottles of beverages.
JP2005350081A2 describes a foam cap made from foam plastic for recycling purposes that has a larger external diameter and therefore makes providing more torque somewhat easier. Such a lid is, however, bulky and unaesthetic.
The literature also includes a number of lids for PET bottles that have appendages for other functions. For example, JP2004338763A2 and JP2000281115A2 describe lids with integral hooks. NL1035643C2 describes a lid with an integral clip. JP2004043008A2, JP2006036264A2 and GB2403202A describe lids that also serve as drinking Cups. Such lids are more massive and enable an increased torque that aids leverage, making opening easier but this is not the main point of such appendages which are usually quite bulky. They are considerably more expensive to manufacture than regular lids, being more bulky and using more raw material. They are also difficult to manufacture putting the costs up somewhat.
JP2010240212A2 titled “Lid Member Mounting Toy” describes a lid that serves as the enlarged head of a doll type toy, with a small body attached thereto, perpendicularly. Such a cap will be expensive to manufacture.
Furthermore, it will be appreciated that many soft drinks contain large amounts of sugar, or in diet versions, contain artificial sweeteners that have been claimed to be unhealthy or even carcinogenic. Some soft drinks that are frequently vended in PET bottles contain phosphoric acid and caffeine and have been accused as being addictive. Manufactures of such drinks prefer to aim their marketing campaigns to young adults rather than to children. In addition to high construction costs, a doll like lid is rather gimmicky and not appropriate for a drink aimed at adults.
A number of tools have been proposed that engage a bottle lid and provide additional leverage, thereby facilitating opening such bottles. Such tools include
JP2000309395A2 , JP2009126517A2, JP2011025963A2, JP09040084A2
JP2004359265A2describes yet another PET bottle cap remover. JP2004338763A2 describes a C shaped adapter with a protruding hook made from polyester resin. The C shaped part engages the bottle cap and the protruding hook helps provide leverage. The C shaped part engages the bottle cap and the protruding hook helps provide leverage.
JP2002145270A2 describes a bottle cap remover built into the base of a PET bottle, so one bottle can be used to remove the lid of another bottle.
JP2011073779A2 describes a bottle opener that can be reversed and used as a replacement cap. The device extends radially further than the skirt of a regular PET bottle and thereby facilitates ease of opening.
Another approach is described in EP0199408A1 which describes using a lubricant to make lid removal easier.
The plethora of approaches that have been suggested that address the issue of removing tight fitting lids from PET bottles, indicates that there is a real issue with the ubiquitous caps that are widely used.
There is a need for a more easily removable lid appropriate for PET bottles containing beverages aimed at the sophisticated adult market and the present invention addresses this need.